SHARON, N.D. -- Chris Johnson has seen double before during spring calving.

But never like this.

Of the 300 cows that have given birth so far this spring on his family's ranch, 50 -- or roughly 16 percent -- have had twins.

Yes, you're reading that correctly.

"It's 50 sets of twins. Fifty cows, 100 calves; all twins, no triplets. I know it's probably a little hard to believe," said Johnson, who ranches with his dad, Keith; uncle, Wayne; and brother, Jeremy.

"We've had twins here before. But nothing like what we're seeing this year," Chris Johnson said.

"There have been days we've gone out and found (newly born) twins. Then, we go back out a few hours later and there's another set of twins. You start asking yourself, 'Is this really happening?'" he said.

Two by two

About 500 Simmental/Red Angus cows will give birth between early February and June this year on the Johnson Stock Farm near Sharon.

Johnson was told by a veterinarian that about 3 percent of beef cows give birth to twins. At that rate, the Johnson operation could expect 15 sets of twins by the end of calving.

So, why all the twins for the Johnsons?

The upturn might be a one-year fluke with no underlying cause, Johnson said.

If there is a reason, "it might be genetics. Or it might be the (excellent) weather last fall," he said.

Another possibility is that the cows are eating dried distiller's grain from the ethanol plant in Casselton, N.D., Johnson said.

"Maybe it's one of those things or a combination. We just don't know," he said.

Sire lines can influence the percentage of twin births, and Simmentals are a breed in which the trait is found, said Bethany Funnell, veterinarian with the University of Minnesota Extension's North Central Research and Outreach Center in Grand Rapids, Minn..

Cows with good body condition also can be more likely to conceive twins, she said.

Dried distiller's grain is high in protein and can help improve a cow's body condition, she said.

There are several potential explanations for the spike in twin births, said Charlie Stoltenow, North Dakota State University Extension Service veterinarian.

The calves that cattle producers keep as replacement heifers sometimes have greater odds of giving birth to twins, a trait of which the producer isn't always aware, he said.

Another possibility is that all the conditions encouraging twinning came together at the right time in the Johnson cows' reproductive cycle.

The big increase in twinning also could be an anomaly, Stoltenow said.

He's not aware of a widespread or regional increase in twin calves born this spring.

Bonus or burden?

In theory, ranchers appreciate twins; there's one more animal to sell. But the reality can be somewhat different.

Calving difficulties are more common with twins, which can cause more dead calves, higher vet bills and extra effort and hassle for the rancher.

Several sets of twins born this spring on the Johnson operation died, as did several individual twins.

Even when both newborn twins are healthy, ranchers face additional work. The twins' mother often can't provide enough milk for both calves, so one must be bottle-fed.

One of the two also could be transferred to a cow that lost her own calf, if such a cow is available. But getting the cow to accept the other calf requires time and effort from the rancher.

"I'd trade twins for one healthy calf anytime," Johnson said. The dry spring and good calving conditions so far are appreciated, Johnson said.

But what he and other family members will remember most about this calving season is the torrent of twins.

"Fifty sets of twins. And there'll probably be some more before we're done," he said.